The chemical treatment of niobium (Nb) superconducting RF (SRF) cavities, such as those used in nuclear physics research, is an expensive and complex multistep process. Furthermore, after such treatments, the cavity¿s surfaces still have numerous bubbles and pits that result from welding. These quench-producing weld defects, together with particulate contamination, result in a significant degradation of the performance of multi-cell Nb SRF cavities. This project will develop a new chemical-free processing technology for multi-cell Nb SRF cavities. The approach uses an internal electron gun to smooth, clean, purify, and eliminate voids, steps, pits, and other defects, as well as particulate contaminates, from the cavity interior surfaces made of Nb-sheet. Commercial Applications and other Benefits as described by the awardee In addition to its applications for DOE facilities, the proposed process could be implemented with minor modifications into the manufacturing of many other types of RF devices, both superconducting and normal conducting